org.apache.hadoop.hive.ql.udf.generic

Class GenericUDAFLeadLag

java.lang.Object

org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver

org.apache.hadoop.hive.ql.udf.generic.GenericUDAFLeadLag

All Implemented Interfaces:

GenericUDAFResolver, GenericUDAFResolver2

Direct Known Subclasses:

GenericUDAFLag, GenericUDAFLead

public abstract class GenericUDAFLeadLag
extends AbstractGenericUDAFResolver

abstract class for Lead & lag UDAFs GenericUDAFLeadLag.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GenericUDAFLeadLag.GenericUDAFLeadLagEvaluator

Constructor Summary

Constructors

Constructor and Description
GenericUDAFLeadLag()

Method Summary

Methods

Modifier and Type	Method and Description
protected abstract GenericUDAFLeadLag.GenericUDAFLeadLagEvaluator	createLLEvaluator()
protected abstract String	functionName()
GenericUDAFEvaluator	getEvaluator(GenericUDAFParameterInfo parameters) Get the evaluator for the parameter types.

Methods inherited from class org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver

getEvaluator

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GenericUDAFLeadLag

public GenericUDAFLeadLag()

Method Detail

getEvaluator

public GenericUDAFEvaluator getEvaluator(GenericUDAFParameterInfo parameters)
                                  throws SemanticException

Description copied from interface: GenericUDAFResolver2

Get the evaluator for the parameter types. The reason that this function returns an object instead of a class is because it is possible that the object needs some configuration (that can be serialized). In that case the class of the object has to implement the Serializable interface. At execution time, we will deserialize the object from the plan and use it to evaluate the aggregations.

If the class of the object does not implement Serializable, then we will create a new instance of the class at execution time.

Specified by:

getEvaluator in interface GenericUDAFResolver2

Overrides:

getEvaluator in class AbstractGenericUDAFResolver

Parameters:

parameters - The parameter information that is applicable to the UDAF being invoked.

Throws:

SemanticException

functionName

protected abstract String functionName()

createLLEvaluator

protected abstract GenericUDAFLeadLag.GenericUDAFLeadLagEvaluator createLLEvaluator()